The present invention relates to machine collets, and more particularly to a collet for use with taps.
As understood in the art, conventional taps require a relatively high degree of rotational torque for operation. Thus, the tool holding device, such as a tap collet, must be able to transmit the high rotational torque to the tapping tool. The tap itself has a round shank portion and a multi-sided rear shank portion. Typically, the multi-sided portion comprises a square profile. Split steel tap collets are known in the art for positively driving a tap having a tap square as described above. Kennametal, Inc. of Latrobe, Pa., manufactures and sells such a split steel tap collet. The conventional split steel tap collets, however, have a significant drawback in that they are relatively ineffective as sealing collets in situations wherein it is desired to conduct a coolant fluid to the tap through the collet. Due to the open spaces between the split steel gripping surfaces and the open sides of the square portion of the tap corresponding to the tap square, an effective seal cannot be obtained with this type of split steel tap collet. In many applications, it is highly desirable to conduct a relatively high pressure coolant fluid to the working surfaces of the tap through the collet and associated tool holder. Conventional split steel collets have proven relatively ineffective in this situation.
The Jacobs.RTM. Chuck Manufacturing Company manufactures and markets a well known Rubber-Flex.RTM. collet of the type having a plurality of individual independent gripping members held in position and equally spaced about a common axis. The spaces between the gripping members is filled with an adherent resilient material, such as rubber or a rubber composition. The benefits of the Rubber-Flex.RTM. collet over conventional split steel collets in both gripping strength and in sealing applications are well known to those skilled in the art. However, it was previously not thought of to utilize a Rubber-Flex.RTM. collet as a tap collet due to the relatively high rotational torque required for tap collets. Thus, the benefits of a Rubber-Flex.RTM. collet have generally not been recognized or appreciated in the tap collet line.